I use simple green and water. I install the factory filter and run it because it takes a few days for the Airaid filter to get good and dry. I spray the simple green on the filter from the "clean side"(throttle body side) so when you rinse it the dirt is going towards the bottom of the air box(the direction it came from). This prevents the dirt from getting buried deeper in the filter, so I've been told. Hope this makes sense and helps.
If you read the instructions that come with the filter it will guide you through the process. But who reads the instructions these days.
